Unfortunately C++ ended up with a set of defaults (i.e., the most ergonomic ways of doing things) that are almost always the least safe. During most of C++'s development, performance was king and so safety became opt-in.

Many of these can't be blamed on C holdover. For example Vector.at(i) versus Vector[i] – most people default to the latter and don't think twice about the safety implications. The irony is that most of the time when people use std::vector, performance is irrelevant and they'd be much better off with a safe default.

Alas, we made our bed and now we have to lie in it.